title: Combating resistance to anti-IGFR antibody by targeting the integrin β3-Src pathway.
abstract: BACKGROUND
  Several phase II/III trials of anti-insulin-like growth factor 1 receptor (IGF-1R) monoclonal antibodies (mAbs) have shown limited efficacy. The mechanisms of resistance to IGF-1R mAb-based therapies and clinically applicable strategies for overcoming drug resistance are still undefined.
  
  
  METHODS
  IGF-1R mAb cixutumumab efficacy, alone or in combination with Src inhibitors, was evaluated in 10 human head and neck squamous cell carcinoma (HNSCC) and six non-small cell lung cancer (NSCLC) cell lines in vitro in two- or three-dimensional culture systems and in vivo in cell line- or patient-derived xenograft tumors in athymic nude mice (n = 6-9 per group). Cixutumumab-induced changes in cell signaling and IGF-1 binding to integrin β3 were determined by Western or ligand blotting, immunoprecipitation, immunofluorescence, and cell adhesion analyses and enzyme-linked immunosorbent assay. Data were analyzed by the two-sided Student t test or one-way analysis of variance.
  
  
  RESULTS
  Integrin β3-Src signaling cascade was activated by IGF-1 in HNSCC and NSCLC cells, when IGF-1 binding to IGF-1R was hampered by cixutumumab, resulting in Akt activation and cixutumumab resistance. Targeting integrin β3 or Src enhanced antitumor activity of cixutumumab in multiple cixutumumab-resistant cell lines and patient-derived tumors in vitro and in vivo. Mean tumor volume of mice cotreated with cixutumumab and integrin β3 siRNA was 133.7 mm(3) (95% confidence interval [CI] = 57.6 to 209.8 mm(3)) compared with those treated with cixutumumab (1472.5 mm(3); 95% CI = 1150.7 to 1794.3 mm(3); P < .001) or integrin β3 siRNA (903.2 mm(3); 95% CI = 636.1 to 1170.3 mm(3); P < .001) alone.
  
  
  CONCLUSIONS
  Increased Src activation through integrin ανβ3 confers considerable resistance against anti-IGF-1R mAb-based therapies in HNSCC and NSCLC cells. Dual targeting of the IGF-1R pathway and collateral integrin β3-Src signaling module may override this resistance.
authors.affiliation: Affiliations of authors: Department of Thoracic/Head and Neck Medical Oncology (DHS, SPC, FMJ, SML, BSG) and Department of Experimental Therapeutics (KM), The University of Texas MD Anderson Cancer Center, Houston, TX; College of Pharmacy, Inje University, Gimhae, Gyungnam, Republic of Korea (H-JL); College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea (H-YM, M-SL, JWL, H-YL).
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Shin
authors.forename: Hyo-Jong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Min
authors.forename: Sun Phil
authors.initials: SP
authors.lastname: Choi
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Lee
authors.forename: Jung Weon
authors.initials: JW
authors.lastname: Lee
authors.forename: Faye M
authors.initials: FM
authors.lastname: Johnson
authors.forename: Kapil
authors.initials: K
authors.lastname: Mehta
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lippman
authors.forename: Bonnie S
authors.initials: BS
authors.lastname: Glisson
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Lee
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D000081247:CSK Tyrosine-Protein Kinase; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D039661:Integrin beta3 / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy; D051379:Mice; D008819:Mice, Nude; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects*; D000077195:Squamous Cell Carcinoma of Head and Neck; D023041:Xenograft Model Antitumor Assays; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D039661:Integrin beta3; D047428:Protein Kinase Inhibitors; C557414:cixutumumab; D017526:Receptor, IGF Type 1; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D051057:Proto-Oncogene Proteins c-akt